1. Field
The present disclosure generally relates to manufacturing and reworking of adhesively bonded cell-based arrays, and deals more particularly with a method and apparatus curing the adhesive that bonds the cells and skin panels together.
2. Background
Cell-based structural arrays may be used to provide composite structures with strength and rigidity, and/or to form functional features such as a structural RF (radio frequency) aperture used for transmission and/or reception of RF signals. In one application, a cell-based structural array is bonded between inner and outer facesheets to form a sandwich structure. The cell-based structural array comprises individual hollow cells formed by cell walls that are adhesively joined together along bondlines. After the adhesive is applied, a bank of tooling blocks is inserted into the cells of the array, and the array along with the tooling blocks are placed in an oven or an autoclave for thermal curing.
The curing technique described above relies on convection heat sources which may not evenly convect heat across the bank of tooling blocks. This uneven convection heating is due in part to thermal gradients caused by the relatively high thermal mass of the tooling blocks. Uneven convection heating may result interior sections of the cell-based array heating up more slowly than the outer sections. Additionally, uneven heating may occur within the individual cells where the tooling blocks have insufficient thermal conductivity to conduct heat uniformly through the interior of the cells. Again, this non-uniform heat conduction, particularly in remote regions of the tooling blocks, is due to the relatively high thermal mass of the tooling blocks.
As a result of these causes of uneven cell heating, the bonding adhesive may not be cured with sufficient uniformity across all cells of the array to meet process specifications, resulting in scrap or rework which adds to manufacturing costs.
Accordingly, there is a need for a method and apparatus that provide consistent, uniform heating of adhesively bonded cell-based arrays during thermal curing. There is also a need for a method and apparatus of the type mentioned above that reduces the fabrication cost of composite sandwich structures, increases production yields and reduces the time required for thermal curing.